Japan's defense chief, Shigeru Ishiba, on Monday ordered the dispatch of ground troops to Iraq for humanitarian duties and reconstruction work. The order came hours after the Japanese government cleared the final political obstacle to the dispatch of troops to Iraq. The decision means Japanese soldiers will be operating in a combat zone for the first time since World War II.

Japanese Prime Minister Junichiro Koizumi on Monday secured the backing of his coalition partner, the New Komeito Party, to send 600 ground troops to Iraq. New Komeito leader Takenori Kanzaki told Mr. Koizumi he would support the dispatch, leaving the government free after months of debate to deploy the troops.

The first contingent of the 600 is expected to depart for Iraq on February third. The troops will assume a non-combat role, purifying water, supplying medical equipment and rebuilding public facilities.

Nevertheless, the deployment marks the first time Japanese troops will operate in a war zone since World War II.

Japan's post-war constitution bars the use of force to resolve international conflicts, but a special law was passed last year allowing any Japanese troops sent to Iraq to defend themselves if attacked.

In an address to lawmakers Monday, Mr. Koizumi sought to calm public concerns over the deployment. He says Japanese troops are welcomed by many Iraqi people. He adds that the troops will help Iraqi people by performing only non-combat duties.

But many Japanese have expressed reservations about the decision. They fear the soldiers will be attacked by insurgents, especially after two Japanese diplomats were killed in Iraq in November. They are also worried about threats terrorist groups have made to attack Japan in retaliation for the deployment. More than 350,000 people protested the planned dispatch Sunday in downtown Tokyo.

However, a poll published Monday in the Mainichi newspaper shows that public opposition to the plan has decreased somewhat, to 47 percent from 54 percent, since last month. Mr. Koizumi has repeatedly told the public that the mission is relatively safe and has underscored the importance of helping stabilize Iraq.

An advance team of about 100 Japanese air force personnel is already in Kuwait to provide support for the ground troops that will be arriving soon in Iraq. In total, Japan will be sending about one-thousand military personnel to Iraq and other countries in the region.